The ability to route, redirect and control the flow of electromagnetic radiation is important in a number of technological applications. Optical information systems, for example, are expected to become increasingly important as the demand for high speed and high density transmission and storage of data escalates. In order to optimize the functionality of optical devices, it is necessary to exercise precise control over the direction of propagation of light. Reading and writing of optical data, for example, typically requires precise positioning of one or more optical beams at well-defined locations within an optical recording medium. In many applications, it is also desirable to exact control over the propagation of light with increasingly compact devices. Miniaturization and enhanced functionality of optical components are essential for future technologies. Similar capabilities are desired for electromagnetic frequencies outside the optical range.
Traditional devices for controlling the propagation of electromagnetic radiation include reflecting elements such as mirrors arid beam splitters, focusing elements such as lenses and parabolic mirrors, and dispersive elements such as prisms. These devices, of course, have proven to be remarkably reliable and effective at directing light in intended ways, but suffer from the drawback that once fabricated and-positioned, their ability to control the propagation of electromagnetic radiation is fixed. Any change in propagation requires a physical movement of the device and may involve cumbersome and/or slow alignment procedures.
Efforts at miniaturizing devices for controlling the propagation of electromagnetic radiation have recently focused on MEMS (micro-electro-mechanical systems) technology. MEMS components are small, lightweight and capable of routing electromagnetic radiation in miniature device packages. MEMS technology includes miniature mirrors configured in arrays that may contain several hundred mirrors that are precisely positioned and/or tilted relative to each other. MEMS is a potentially advantageous technology because the component masses are very and thus require little force for the repositioning necessary to achieve a dynamic performance capability. Most efforts at developing MEMS technology have focused on optical switching and optical cross-connects. MEMS technology may be used, for example, to direct optical signals to specific fibers in a fiber bundle and to redirect a signal to other fibers upon repositioning.
Although MEMS technology offers several potential advantages, its' implementation presents several problems. First, although MEMS components are repositionable, the repositioning is through a mechanical process and occurs on a millisecond timescale. Faster dynamic capability is desirable for many applications. Second, MEMS systems are delicate and susceptible to disruptions caused by external disturbances such as vibrations. These disturbances alter the positioning of MEMS components and impair functionality. Complicated feedback systems may thus be needed to insure robustness of operation in typical application environments. Third, MEMS systems are currently very expensive. The high cost is associated with the intricacies of fabricating the miniature components, the large number of components typically required for an application, and the precise assembling of components, along with actuating means, into the three-dimensional arrays required for many applications.
Accordingly, improved devices for controlling the propagation of electromagnetic radiation are needed in the art. Ideally, these devices should be stationary, dynamically reconfigurable, and provide for the reflection and redirection of electromagnetic radiation in an efficient, reproducible manner in user-determined directions spanning a large range of angles.